The present invention relates to new compounds having therapeutic effect and a method for preparing thereof. Some of the new compounds are ingredients of the plant belonging to Genus Rubia and others are derivatives of the ingredient.
Up to now, there have been many attempts to obtain antineoplastic extracts from plants. Among such extracts, such as alkaloid-containing material extracted from a plant of colchicum autumnal (J. Chem. Soc., 1940, 194) or vinca rosea (J. Am. Chem. Soc., 1964, 86, 1440); one kind of lignan from podophyllum peltatum (J. Am. Chem. Soc., 1953, 75, 235); and anthamacrolidic material having a similar molecular structure to rifamycin, which is extracted from a plant of celastraceae are well known. In addition, among materials extracted from a lower plant, mushroom, protein-polysaccharide body extracted from coriolus versicolor is, for instance, well known and has already been on the market (GAN TO KAGAKURYOHO, 1974, 1, 251). Nevertheless, only a few of these extracts have practically been utilized as a medicine.
Furthermore, a number of workers have made great efforts to obtain a single product having an exellent pharmacological action from plants, however, only a few of the workers succeeded in such attempt.
On the other hand, a number of studies have been carried out in order to get these kind of medicine by a chemical synthesis, however, almost all studies was discontinued without any remarkable success. This was because such synthetic medicines exhibited serious side-effects.